ipv4: new ip_no_pmtu_disc mode to always discard incoming frag needed msgs

This new mode discards all incoming fragmentation-needed notifications
as I guess was originally intended with this knob. To not break backward
compatibility too much, I only added a special case for mode 2 in the
receiving path.

Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 1a4ee84ca3f3..fb3c5637199d 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -705,7 +705,9 @@ static void icmp_unreach(struct sk_buff *skb)
                 case ICMP_PORT_UNREACH:
                         break;
                 case ICMP_FRAG_NEEDED:
-                        if (net->ipv4.sysctl_ip_no_pmtu_disc) {
+                        if (net->ipv4.sysctl_ip_no_pmtu_disc == 2) {
+                                goto out;
+                        } else if (net->ipv4.sysctl_ip_no_pmtu_disc) {
                                 LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"),
                                                &iph->daddr);
                         } else {